title: Displaceability of SLAP lesion on shoulder MR arthrography with external rotation position.
abstract: OBJECTIVE
  To investigate the usefulness of the external rotation (ER) position on magnetic resonance (MR) arthrography for the diagnosis of superior labral anterior to posterior (SLAP) lesion.
  
  
  METHODS
  Approval of institutional review board was obtained, and informed consent was waived. The MR arthrograms of 210 shoulders that were arthroscopically confirmed as SLAP lesion in 163 shoulders and intact superior labrum in 47 shoulders were retrospectively reviewed in each neutral and ER position for the diagnosis of SLAP lesion, the extent of distraction of the torn labrum, and the external rotation angle. The sensitivity, specificity, and diagnostic accuracy of MR arthrograms for determining SLAP lesion were assessed in each position. For the arthroscopically confirmed group, the diagnosis of SLAP lesion and the extent of distraction about the tear were compared between neutral and ER positions by Fisher's exact test and the paired t-test. The correlation between the external rotation angle and the diagnosis of SLAP lesion, and between the external rotation angle and the differences in the extent of distraction were evaluated in the ER position using the ANOVA test.
  
  
  RESULTS
  Sensitivity and diagnostic accuracy of MR arthrography for SLAP lesion increased from 64.4% and 71.0% in the neutral position to 78.5% and 81.9% in the ER position, respectively, without change of specificity, which was 93.6% in both positions. The diagnosis of SLAP lesion was changed from negative to SLAP lesion in 16.0% of the arthroscopically confirmed group. Mean difference in the extent of distraction about the tear was 0.69 mm (range -1.40 ∼ 6.67 mm), which was statistically significant. There was no relationship between the external rotation angle and the diagnosis of SLAP lesion, and between the external rotation angle and the differences in the extent of distraction.
  
  
  CONCLUSIONS
  Shoulder MR arthrography with additional ER positioning helps in the diagnosis of SLAP lesion and provides information about the displaceability of the torn labrum.
authors.affiliation: Department of Radiology, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea.
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Jung
authors.forename: Doo Hoe
authors.initials: DH
authors.lastname: Ha
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.forename: Marcia F
authors.initials: MF
authors.lastname: Blacksin
authors.forename: Kyung Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Jae Wha
authors.initials: JW
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001182:Arthroscopy; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D009942:Organometallic Compounds; D056888:Patient Positioning; D012399:Rotation; D012680:Sensitivity and Specificity; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000473:pathology
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine